After discussion we agreed that a superhero needs a cape, a mask, and a t-shirt with the superhero motif on it (and no, Matthew did not use the word “motif). His choice of colours was – conveniently – pale blue with red accents. So I found a pale blue sheet in my stash, and a matching t-shirt in his “nearly too small” pile of t-shirts. One red scarf, and some bits of felt later and I was in business.
The silver lightning bolts and the power cuffs were an extra bonus which he loved.
Having had some difficulty finding good guidance online (Mum to the rescue again) I might just try my hand at writing a tutorial on this. You know, when I get a moment.